Steam engine



M. LOTHROP 2 Sheets-Sheet 1 July 19, 1955 STEAM ENGINE Filed Oct. 18, 1954 77 7! INVENTOR.

MIPCl/i 40719909 M. LOTHROP July 19, 1955 STEAM ENGINE 2 Sheets-Sheet 2 Filed Oct. 18, 1954 United States Patent Ofiice 2,713,329 Patented July 19, 1955 STEAM ENGINE Marcus Lothrop, Berkele Calif assignor to The Yuba Manufacturing Company, a corporation Application October 18, 1954, Serial No. 462,818

8 Claims. (ill. 121-127) The invention relates to engines operating on steam, air or other fluid, even water, and is especially concerned with a vehicular engine of the sort shown in Harris et al. Patent No. 2,690,165, issued September 28, 195 4, and assigned to the assignee of the present application. The engine therein disclosed has reciprocating pistons with an inlet poppet valve and an exhaust poppet valve in each cylinder, the valves being operated by cams. There is a shifting mechanism so that different selected ones of the cams can be made optionally effective upon the individual valves. in this way the engine is reversed and the inlet or admission event is cut off at different, selected or desired times in the engine cycle. With separate inlet and exhaust valves, particularly unbalanced poppet valves, the shifting mechanism is of considerable importance and for that reason, the mentioned patent shows a hydraulic shifting arrangement.

In starting a steam engine, especially from cold condition, it is sometimes the case that the inlet steam condenses partly or completely in the inlet line leading to the engine and in the engine itself so that the engine is initially operated with various amounts of water in the incoming fluid. Lubrication is poor in a cold engine, and wear is great if the engine must start under a heavy load when cold. The starting situation is particularly aggravated when the engine has been exposed for a considerable time to very cold surroundings prior to operation.

It is therefore an object of the invention to provide a steam engine having means for mitigating or eliminating the deleterious effects of liquid in the incoming operating fluid.

Another object of the invention is to provide means for warming the engine prior to actual operation.

Another object of the invention is to provide a shifting mechanism effective to assist in warming the engine.

Another object of the invention is in general to provide an improved steam engine.

Other objects, together with the foregoing, are attained in the embodiment of the invention described in the accompanying description and illustrated in the drawings, in which:

Figure l is a diagram of an engine of the sort shown in the mentioned patent, the view being largely in cross section to show the inlet valve and with various parts being eliminated to simplify the disclosure and other parts being broken away to reduce the size of the figure.

Figure 2 is a cross section somewhat similar to Figure 1 showing the shifting mechanism in one extreme position.

Figure 3 is a view comparable to Figure 2 and showing the shifting mechanism in another extreme position.

Figure 4 is a view similar to Figure 1 being largely in cross section and particularly illustrating the exhaust valve and its attendant mechanism.

Figure 5 is a view in side elevation and in cross section, the view being taken along the lines 5-5 of Figure 4.

In the structure illustrated in the drawings, the engine includes a frame 6 made up of various supporting and enclosing components and including a crank case all in the general configuration much like that of the customary internal combustion engine. The engine includes a trunk piston 7 provided with the usual connection to the customary crank shaft (not shown), and reciprocating cyclically within a cylinder 8 in time with the operation of the engine. Leading into the engine at an appropriate point is a steam duct 9 carrying operating fluid under pressure from a suitable source and communicating through a valve opening 11 with a passageway 12 leading into the cylinder 8 above the piston 7. Flow from the duct 9 into the passageway 12 is controlled by an inlet poppet valve 13 having a valve stem 14 arranged for reciprocation in the frame 6. The valve is provided with a closing spring 16 in the usual fashion.

For actuating the valve 13 there is provided an actuator including an inlet lever 17. The lever is pivotally mounted on a rod 13 fixed with respect to the frame 6 and is formed to provide a contacting face 20 in engagement with the stem 14 of the valve 13. The lever is enlarged to provide an axially broad shoe 19 extending axially into locations to be engaged by either one or the other of a pair of cam followers 21 and 22. The cam followers are reciprocably mounted in a ring 23 and are circumferentially spaced apart and are likewise axially spaced apart.

The ring 23 is rotatable within a cage 24 forming part of the frame 6 and is concentric with an axis 26 about which a cam shaft 27 is rotatable. The cam shaft 27 can be either an extension of the crank shaft of the engine to which the piston 7 is connected or can be a separate shaft driven by the crank shaft in the well understood way. The shaft 27 carries cams 28 and 29 which are circumferentially located for different functions in the cycle, such as for forward and reverse admission and cutoff, and are likewise axially spaced along the shaft 27 to engage appropriate rollers 31 and 32 rotatably mounted in the forked ends of the followers 21 and 22, respectively.

When the ring 23 is in one circumferentially shifted position, as shown in Figure 2, the cam 28 is effective upon the follower 21 which is in direct engagement with the shoe 19 on the lever 17 so that events determined by the cam 28 are imposed upon the valve 13. When, however, the ring 23 is in its other circumferentially shifted position, as shown in Figure 3, the cam 29 is effective upon its follower 22 then in engagement with the shoe 19 on the lever 17 so that the valve 13 then partakes of motion derived from the cam 29. When either one of the cams 28 or 29 is effective upon the valve 13, the other cam merely operates its follower idly. By moving the ring 23 between its extreme positions, as illustrated in Figures 2 and 3, either of two motions is imposed upon the valve 13 so that the admission of steam to the cylinder 8 occurs during either of two different periods in the reciprocatory cycle of the piston 7.

A comparable arrangement is provided for the exhaust function. As shown particularly in Figure 4, the frame 6 above the piston 7 is also provided with an exhaust passage 36 communicating with the cylinder 8 through a valve port 37. Flow through the port is controlled by an exhaust poppet valve 38 having a stem 39 and urged toward closed position by a spring 41 in the usual fashion. Motion is imparted to the valve stem 39 through a rocker 42 pivoted on a shaft 43 mounted appropriately on the engine frame 6. The rocker is also in engagement with a push-rod 44 extending through a passageway 46 in the engine frame and in engagement with an exhaust lever 47. Conveniently, the lever 47 is mounted on the rod 18 alongside the lever 17.

The lever 47 has an axially extended shoe 48 of sulficient axial width to be engaged by either one of two exhaust followers 49 and 51. These are axially and cir-- eumferentially spaced apart in the ring 23. When the ring 23 is rotated or shifted to move the inlet followers 21 and 22, the exhaust followers 49 and 51 are similarly moved. On the shaft 27 are exhaust earns 52 and 53' spaced. apart 'axially to engage rollers 54 and 55 rotatably mounted in the forked ends of the followers .49 and 51. Thus motion due to the cam 52 is transmitted through the follower 51 to the valve 38 when the shifting mechanism and the ring 23 are in one'extreme position, whereas motion due to the cam 53 is imparted through the follower 49 to the valve 38 when the shifting mechanism and the ring 23 are in the other extreme position; In this fashion, both the exhaust and inlet valving structures are shifted between forward and reverse positions, for example.

In't-he present instance, the valve mechanism is shifted not only between the two extreme positions necessary to afford actuation of the valves by the respective inlet cams 2S and 29 and the exhaust cams 52 and 53 but likewise is shifted into an additional position. The ring 23, in an appropriate circumferential and axial position, as shown especially in Figures 1, 4 and 5, is provided with a cam button 56 conveniently having approximately the end contour of one of the followers, such as 49 or 21. The button 56 is fixed in position in the ring 23 circumferentially between the followers, such as 21 and 51, and also axially between such followers. In this loca tion, the button 56 can simultaneously engage both the shoe 48 on the exhaust lever 47 and the shoe 19 on the inlet lever 17.

When the ring 23 (and so the button 56) is in an intermediate position, as shown in Figures 1, 4 and 5, none of the followers 21 and 22 or 49 and 51 is in position to be effective upon either the inlet lever 17 or the exhaust lever 47. Instead the button 56 is effective upon both the levers 17 and 47 sothat simultaneously the inlet valve 13 is held open and the exhaust valve 38 is hel open. 7

Under this circumstance, when the valve or throttle controlling the flow of steam or other fluid in the line 9 is opened, the fluid flows through the inlet port 11 into the cylinder 8 above the piston 7 and continues its flow from the cylinder 8 out through the port 37 into the exhaust passage 36. While the pressure of such'fluid is not particularly great and does not exert any substantial force upon the piston 7, the fluid temperature initially is usually relatively high. At first, the heat loss to the engine may beconsiderable so that the final or resulting fluid temperature may not be very great. At first, considerable water may be entrained with the steam, but if so no harm isdone for such water simply carries through the cylinder 8 and flows into the exhaust.

When the flowing fluid has given up enough of its 7 heat to the cylinder walls and the rest of the engine 6,

the engine and lubricating oil temperatures rise so that no more condensation takes place in the engine. The

engine parts and the lubricant rapidly attain fair operating temperatures or substantially so. During this initial or starting blow-through or heating step, any cool water which may previously have condensed in the inlet line 9 is gotten rid of to the exhaust by being conducted through the engine cylinder. The. following operating fiuid'is warmer and is effective. to heat the engine substantially to condition it for assuming its working load. After sufficient flow has taken place through the engine to heat it, and even from an extremely cold condition only a short time is required, the button 56 is shifted out of the way by rotation of the ring 23 into either of the normal extreme positions for forward or. reverse operation. During ordinary shifts of the ring 23 between forward and reverse positions, the button56 is momentarily effective. to open 'both the inlet valve 13 and .theexhaust valve 38 but the shift is accomplished so quickly that this action is but of short duration and is not deleterious.

The shifting mechanism which produces the various positions described is attached to the engine frame 6 and incorporates a cylinder 61 appropriately communicating V with the interior of the frame 6 through an opening 62. Projecting through the opening is a lever 63 fastened to the ring 23 and at its other extremity enlarged to provide a bar 64. Adapted to abut the bar 64 adjacent the ends thereof are two plunger sleeves 66 and 67 designed to reciprocate within the cylinder 61 and provided with packing 68 and 69 against leakage. Pistons 71 and 72 also provided with packings 73 and 74 are reciprocable within the sleeves. The pistons 71 and 72 have plungers cylinder 61 are closed by plugs 79 and 81 (Figure 2)..

The plug 79 is provided with an opening 82 connected to a source of hydraulic fluid under pressure Whereas the plug 81 is similarly provided with an opening 83 connected to the source of pressure fluid. These connections are under the control of an appropriate valve such that pressure can be exerted through the opening 82 alone, through the opening 83 alone, or through the two openings 82 and 83 simultaneously. When fluid pressure is exerted through either one of the openings alone, the pressure upon the other opening is released.

In the operation of this structure, pressure fluid is admitted through the opening 82, for example, as shown in Figure 2. The pressure is exerted over the entire face of the sleeve 66 and of the piston 71 and no pressure is imposed upon the sleeve 67 and the piston 72. The piston 71 and its surrounding sleeve 66 are then translated simultaneously toward the right in Figure 2 until the sleeve abutsv the barrier 78 and is stopped. There is no restraint, however, upon further movement of the piston 71 which continues its translation toward the right so that the plunger 76 shifts the lever 63 into its ex- 'the sleeve 67 and upon the piston 72, the parts moving until the sleeve 67. abuts and stops against the barrier 78 while the piston 72 and its plunger 77 continue until the lever 63 abuts the sleeve 66 against the plug 79. Tov shift from one extreme position to the other, pressure fluid is'exerted upon either the opening 82 or the opening 83.

When both inlet and exhaust valves are to be opened for the initial blowing of a heating medium through the cylinder 8,. pressure fiuid is simultaneously admitted through both openings 82 and 83. In that. instance, both of the sleeves 66 and 67 are subjected to pressure until they both abut the barrier 78. The bar 64, being in contact with both of the sleeves 66 and 67, is therefore. brought to a central position in alignment with the barrier 78. There is equal pressure upon both of the cylinders 71 and 7.2 so that the lever 63 is readily-cemtralized. The ring 22 is thus positioned with the button 56in camming or displacing position under the shoe 48 on the lever 47 and the shoe 19 on the lever 17. This is the position of the parts illustrated in Figures 1 and 4.

In this fashion, there is provided a shifting mecha nism to orient or rotate and hold the r'ing'23 in any selected one of three positions, the extreme positions of the ring affording the usual valve actuation from the inlet cams 23 and 29 and the exhaust cams 52 and 53,

whereas in the intermediate position, the button 56 opens both of the valves 13 and 38 to afford a flow path into, through and out of the cylinder.

What is claimed is:

1. In a steam engine having separate inlet and exhaust valves, means for operating said valves in timed sequence during the operation of said engine, means for transmitting motion from said operating means to said valves, and means for rendering said transmitting means inefiective and for simultaneously opening said inlet and exhaust valves.

2. In a steam engine having separate inlet and exhaust valves, cams for opening said valves in time with the operation of said engine, cam followers for transmitting motion from said cams to said valves, means for moving said cam followers out of motion transmitting relation ship with said valves, and means operated by said moving means for opening both said inlet and exhaust valves.

3. In a steam engine, an inlet poppet valve, an exhaust poppet valve, an inlet cam and an exhaust cam driven by said engine, cam followers shir'table into and out of a position for transmitting the motion of said cams to actuate said valves, and means for opening said valves when said followers are out of said position.

4. In a steam engine, an inlet poppet valve, a first spring for urging said inlet valve toward closed position, an exhaust poppet valve, a second spring for urging said exhaust valve toward closed position, an inlet cam driven by said engine, an exhaust cam driven by said engine, a shifting member movable with respect to said cam. tappets mounted in said shifting member and movable therewith while in engagement with said cams, separate valve actuation in a first position of said shifting member in engagement with respective ones of said tappets and in a second position of said shifting member out of engagement with said tappets, and a camming member on said shifting member in engagement with both of said separate valve actuators in said second position of said shifting member.

5. In a steam engine, inlet and exhaust cams rotatable about an axis, a cam ring rotatable about said axis, tappets on said cam ring in engagement with said cams, inlet and exhaust valve actuators, a camming member fixed on said cam ring, and means for rotating said cam ring into a first position with said tappets in engagement with said actuators and into a second position with said camming member in engagement with said actuators.

6. In a steam engine, separate inlet and exhaust valves, means operated by said engine for actuating said valves in time with the operation of said engine, and means for interrupting the operation of said valves by said actuating means and for simultaneously opening both of said valves.

7. In a steam engine, separate inlet and exhaust poppet valves, springs for urging said valves toward closed po sition, and means for simultaneously opening said inlet and exhaust valves against the urgency of said springs.

8. In a steam engine, separate inlet and exhaust poppet valves, springs for urging said valves toward closed postion, and a camming member movable simultaneously to open said inlet and exhaust valves against the urgency of said springs.

References Cited in the file of this patent UNITED STATES PATENTS 

